In this book, the first part of Volume 5, the membrane-associated reactions of photosynthesis, namely primary photoreactions, electron transport, and photophosphorylation, are considered. Each of the main sections consists of an introductory review followed by concise articles, in which limited topics are discussed by specialists. This way of presentation certainly will be appreciated by the reader; it facilitates obtaining either general or detailed information, or both. The volume on photosynthesis of the preceding series was published in 1960. In the meantime considerable progress has been made in this field of research. These advances, the resulting change of concepts, and perspectives are dealt with in an introduction by Trebst and Avron as well as in the first section on the history of photosynthesis research during the period 1950-1975 by Amon.